Method and means for the manufac



Feb 2.7, 1945 J. Hr-:uBl-:RGl-:R 2,370,350

METHOD AND MEANS FOR THE MANUFACTURE OF GRAPHITE MOLDS AND THE LIKE Filed June 26, 1942 Patented Feb. 27, 1945 METHOD AND MEANS FOR THE MANUFAC- TURE OF GRAPHITE LIKE MOLDS AND THE f Josef Heuberger, Stockholm,.Sweden,assignor to 'Aktiebolaget Hammarbylampan, Sweden, a companylof Sweden Stockholm,

Application June 26, 1942," Serialo. 448,695

In Sweden August 6,1941 e 6 Claims.

For the manufacture of molds from graphite' or other material, for instance for metal`ceramic purposes, it has been usual to use a pressing contrivance substantially consisting of a press plunger and a matrix,.in which finely divided graphite. Y powder and so forth, with or without adhesive' or other admixtures is pressed, whereupon the .,molds are sintered. In the production of molds of a simple configuration, the pressing of the `matrix. On the other hand, where the production of molds for objects presenting at any point avhelically extending surface, orY part of such a (CLIS-34) the method into effect. I'According to one feature I of such means the press plunger and/or the matrix, which together form the press chamber, and which have one or more helical press surfaces or part of such surfaces, are mounted to rotate freely so that the press plunger and the matrix, in addition to the linear movement in the press stroke of the press plunger,'also may perform a rotating relative movement.

t graphite may beeffected solelyby a rectilinealo movement ofthe press plunger relatively to the` surface, is `brought into consideration, which is1 15 'the case, for instance, with twistl drills or certainY milling-cutters, a methodof this kind cannot be employed. YEspecially Vin, the case of graphite, ,where the material is distinguished by a leaf-like structure, it is desirable that the pressure shall;l

be the sameall over in planes at right angles to the direction of compression'.

" The present invention relates to a method for the manufacture of molds from graphite or similar objects having a helically extending surface,

or part of such a surface, the said manufacture being performed through compression of finely v divided graphite or the like, with or without the addition of other substance, in a matrix by means 'ofa" press plunger. According to the invention i the'press plunger and/or the matrix, or some part thereof, simultaneously with a rectilinear movement are caused to perform a rotary movement relatively to each other throughthe action ofthe pressure resistance of the pressing material against a helical surface on the press plunger y and/or the matrix'.v In order that the condition in regard to the uniform pressure in planes at right angles to the direction of compression shall be maintained it is understood that the rotary .movement must vnot be uniform at a uniform compression of the graphite mass, inasmuch as the relationship between pressure and compression is not a linear one. By reason of the fact that the pressure resistance of the pressing mass itself brings about the rotary movement, the desired positive control of the rotary movement is obtained, which results in that all details of the press plunger and those of the matrix, such as helically extending grooves| are filled with the graphite mass at a uniform pressure, that is to say, without shrinkages or indications of ruptures occurring in the flnished mold. The invention also involves means for carrying According to a further feature ofthe means according the invention,y comprising -a matrix and/or a press plunger consisting of more parts,

only those parts of the device 'are mounted to rotate freely,`which carry helical press surfaces or are actuatedjby such surfaces during the pressing operation. f

In order to facilitate the mounting of the plunger and/or the matrix, it may be found suitable to cause one of the elements, for instance the press plunger, to perform the rectilinear movement, while the other element, such as the matrix or some partthereof, is arranged to perform the rotary movement.

The accompanying drawing illustrates some ,embodimenty of an arrangement according to the invention by way of diagrammatic representation. Figure l shows the use of a rotary press plunger,

and Figure 2 shows a rotary matrix. Figure 3 illustrates a cross section of a matrix having an internal threaded surface.

According to Figure 1, the press plunger 2, which is provided with spiral- (helical) shaped surfaces 3, is rectilinearly movable in relation t0 the matrix 4, which is provided with a bottom piece 5. At the same time, the press plunger is also mounted to be freely rotatable, for instance by means of ball bearings l. In the production ofthe mold, the graphite mass, admixed, if desired, withadhesive and othersubstances, is filled into the matrix, whereupon the press plunger is pressed into this mass. Through the pressure of the graphite mass against the spiral-shaped surfaces the plunger is caused to rotate at the same time, so that it will be screwed into the mass, so t0 say, the pressure being thus Amaintained uniform. The presssing of the mold having been finished, the press plunger may again be readily screwed out, but if desired, it may be left in the mold during the subsequent sintering operation.

In the embodiment according to Figure 2, the rotary movement has instead been allotted to the matrix, while the press plunger only performs the rectilinear movement. To this end, the matrix 4 with its bottom piece may be fixedly or removably arranged on a freely rotatable table 6. The

mounting may be effected with the aid of suitable ,thrustbearings for instance by vmeans of roller bearingsl, which are arranged between the table and a base plate 8. The ba'se plate and the table may be .associated by Ameans of ya pin 9 which is relieved ofV load .bymeans of a thrustbearing yIfll. Dust shields II,- |2 may be provided for the bearings.

It is also possible i form the rectilinear movementjwhile the press plunger is freely rotatable. 1 I-f the matrix or the press plunger is made from a plurality of mutually movable parts, only Ithe mem-ber cooperating with the spiral-groove need be rotatable.

Figure 3 shows sucha device adapted to'shape from graphite or similar material amold with an exterior helical surface.l The matrix i3 has a recess I4 adapted to receive the graphite powder land this recess has an internal screw thread I5 corresponding 4to the helical surface to 'be vpron duced. The plunger 2 is provided with an extension I6. producing a recess in thennished product `to be molded. Thelmatrix is freely rotatable for example by means of bali'bearings I1 arranged at the bottom of the matrix.' v Under the action of the lpressure ofthe graphite mass against the threaded surface i5 upon pressing the plunger 2 downwards'the matrix 'i3 will Vbecaused to rotate so that `a uniform l,pressure is produced in the graphite compressed. f

As manychanges couldbe made in the above `method and construction andmany apparently 'widely different embodiments 'of -the invention could 'be made Without departing from `the scope thereof, las defined by the `following claims, it is intended that all matter contained in the above description shall be interpreted as illustrative and not "in a llimiting sense.

What I yclaim ist l. In a method of @producing graphite molds and Asimilar objects having at -Vleast in part a helically-'extending surface, the -steps of compressing `nelvydivided` 4graphite in a press com- `:prising amatrix and ya press plunger, one of said matrix andplunger having a helically extending surface and effecting, during the vcompressing operation, simultaneously a relative rectilinear i and rotary movement l'oetween the press plu-nger andthe matrix, said rotary movement being ef fected automaticallyby action, during said rectilinear movement, of the pressure Iresistance vof Athe ypressing mass against the helically extending surface- `on said one Yof vsaid vmatrix and plunger.

2. In a method `-of producing graphite molds and similar objects having at least in part a helically Vextending surface, the steps of com- '..pressing neiy `divided 4graphite'in a press comprising a matrix Aand a press :plunger having a.

helicallyiextending surface,fa.nd reflecting, during the compressing operation, simultaneously a relato cause the matrixl topern tive rectilinear and rotary movement between the press plunger and the matrix, said rotary movement being effected automatically by the action, during the said rectilinear movement, of the pres- `sure resistance of the pressing mass against the *helically .extending surface on the press plunger. `3. In a method of producinggraphite molds vand similar objects having at least in partl a similar objects having at least inA part a helically extending surface, *by compression of finely di Avided graphite, comprisingin combination -a press plunger and a matrix, which together form "a,

pressing compartment and which vpossess at least one helical pressing surface, said plunger and matrix being linearly movable toward each other for compressing 4said graphite, and journal means lfor mounting oneof saidpress plunger and matrix for rotary movement relative tothe other duringsaid relative linear movement and compression.

5. Means for producing graphite molds and similar objects 'having at least in part a helically extending surface, by compression of finely divided graphite, comprising in combination a twopart press plunger and a matrix, which together form a pressing compartment and which possess at least one helical :pressingA surface, said press plunger and matrix .being linearly movable toward each other for compressing said graphite, `and 'journal means :for mounting .one part of said -press plunger for `rotary movement relative to the other part andrelative t0 said -matrixdurng said relative linear movement and compression.

6. Means .for producing graphite molds and .d 'similar l.objects lhaving at least in parta helically vextending; surface, b y ,compression of finely divided graphite, comprising in combination a press plunger and a. two-part matrix, which together forma .pressing compartment .and which possess at least one.' helical vpressing surface, .said press .plunger and matrix being .linearly movable Vtoward eachother lfor compressing said graphite,

`and vjournal,means for Vmounting one partei said matrix foltrotarymovement relative to the other party and relative to said press' plunger during said relative linear movement and compression.

` v,JOSEF HEUBERGER. 

